It is often desirable to attach various types of elements to variously proportioned concrete slabs. For example, one may wish to suspend pipes, cables or other equipment from the underside of a concrete bridge deck or other poured concrete ceilings. One commonly used insert or anchor is a cast cylindrical member with an axially drilled threaded hole for screwing in pipe hangers and the like, with outer projections and/or circumferential ridges to resist pulling of the anchor out of the concrete.
Another anchor or insert has a flat rectangularly-shaped base with a threaded hole in its center and an inversely L-shaped bolt extending upwardly from its base as shown in FIG. 1. The base of the insert is nailed to a wooden form with the inversely L-shaped bolt being hand-wired to a reinforcing bar. Concrete is then poured into the wooden form. Once the concrete cures, the form is removed leaving the inversely L-shaped bolt embedded in the concrete slab and the threaded hole in its base exposed and ready for use.
A problem encountered in using such anchors is that due to their shape, the anchors stand the risk of pulling out of the concrete slab if a sudden or extreme force, such as would be caused by an earthquake, explosion, ship collision into a bridge, or even heavy traffic vibration, is applied to it.